The present invention generally relates to methods and equipment for performing size reduction operations on products, including but not limited to food products.
Various types of equipment are known for reducing the size of products, for example, slicing, strip-cutting, dicing, shredding, and/or granulating food products. Certain types of equipment are sometimes referred to as transverse slicers that, as schematically represented in FIGS. 1 and 2, utilize a rotating cutting wheel 10 having radially-extending cutting knives or blades 12 that define a cutting plane through which products 16 are advanced, for example, on a conveyor belt 18, toward the wheel 10 in a feed direction. The cutting wheel 10 typically rotates about a horizontal axis 14 to define a vertical cutting plane. A particular cutting wheel disclosed in U.S. Pat. Nos. 5,992,284 and 6,792,841 is commercially known as the Microslice®, manufactured by Urschel Laboratories, and utilized in a variety of size-reduction machines offered by Urschel Laboratories. The blades of the Microslice® cutting wheel transversely slice products advanced through the cutting plane in a rapid manner to enable high volume production of product slices 20, for example, food slices, of substantially uniform thickness.
FIG. 3 depicts certain aspects of cutting wheels of the type disclosed in U.S. Pat. Nos. 5,992,284 and 6,792,841. Similar to the cutting wheel 10 of FIGS. 1 and 2, FIG. 3 represents a cutting wheel 22 having a rim portion 24 surrounding a hub portion 26, which together support truncated triangular-shaped cutting knife assemblies 28 by means of fasteners 30 so that each knife assembly 28 spans the radial distance between the rim and hub portions 24 and 26 of the cutting wheel 22. Each knife assembly 28 includes a knife blade 32 (shown with hidden lines) carried by a knife holder 34. As evident from FIG. 3, each knife holder 34 has a truncated triangular shape such that the holders 34 have wider and narrower ends, with their wider ends 44 connected to the rim portion 24 and their narrower ends 46 connected to the hub portion 26. Only the cutting edges 36 of the blades 32 are visible in FIG. 3, as the view is that of the side of the cutting wheel 22 facing products as they approach the wheel 22, with the rotation of the wheel 22 indicated by the arrow. Each knife holder 34 defines a registration surface 38 (also referred to as a gauging surface) against which products abut and register during slicing thereof. Each registration surface 38 terminates at a trailing edge 40 that is oppositely-disposed from the cutting edge 36 of the same knife assembly 28, faces the cutting edge 36 of the next adjacent (trailing) knife assembly 28, and cooperates with the cutting edge 36 of the trailing knife assembly 28 to define a gate 42 therebetween. The registration surface 38 and trailing edge 40 of each knife assembly 28 are offset from the cutting edge 36 of the trailing knife assembly 28 in the feed direction (perpendicular to the cutting plane of the wheel 22), such that the gate 42 therebetween defines a slice thickness gap that determines the thickness of a slice produced by the trailing knife assembly 28.
FIGS. 4 and 5 depict views of a knife assembly 28 of the type shown in FIG. 3, and FIGS. 6 through 9 depict various views of the knife holder 34 of the knife assembly 28. The knife holder 34 is generally planar, its trailing edge 40 is relatively blunt, and its oppositely-disposed leading edge 96 has a beveled surface 94. Other than the beveled surface 94 and the registration surface 38 (recessed as discussed below), the holder 34 has a uniform thickness, t1 between oppositely-disposed surfaces 64 and 66 thereof (FIGS. 7 through 9). The knife holder 34 includes fastener receiving apertures 98 through which appropriate fasteners may be received for securing the assembly 28 to the rim and hub portions 24 and 26 of the cutting wheel 22. A knife retainer or clamp 100 is provided, having fastener-receiving apertures 102 through which fasteners 104 extend for assembling the knife clamp 100 to the surface 64 of the knife holder 34 opposite the registration surface 38 and therefore facing away from products approaching the cutting wheel 22. The knife blade 32 is mounted on the beveled surface 94 of the knife holder 34 and secured by the knife clamp 100 and fasteners 104, which are received in threaded apertures 110 in the knife holder 34. The blade 32 preferably further includes apertures 112 that can be aligned with studs 114 on the knife holder 34 to accurately locate the blade 32 on the knife holder 34 and prevent movement of the blade 32 relative to the knife holder 34 after the knife clamp 100 has been secured on the knife holder 34 by the fasteners 104, as illustrated in FIG. 5. The knife clamp 100 may include bores 116 that accommodate the studs 114 and may also engage the studs 114 for alignment and securing purposes.
The registration surface 38 of the knife holder 34 is visible in FIGS. 6 through 9. Relative to the surface 66 at the ends 44 and 46 of the holder 34, the registration surface 38 is recessed in the holder 34 by machining or forming the holder 34 to slope progressively from the leading edge 96 of the knife holder 34 toward its trailing edge 40. The knife holder 34, as noted previously, includes a relatively wider end 44 and a relatively narrower end 46. In order to obtain a uniform slice thickness gap at the gate 42 (FIG. 3) adjacent the trailing edge 40 that will yield slices of uniform thickness produced by the following knife assembly 28, the thickness (t3) of the trailing edge 40 where it intersects the registration surface 38 must be uniform between the wider and narrower ends 44 and 46 of the holder 34. Therefore, the registration surface 38 tapers from the leading edge 96 toward the trailing edge 40 so that its depth (t2) is uniform at its intersection with the trailing edge 40 between the wider and narrower ends 44 and 46 of the holder 34 (FIG. 7). Consequently, the slope of the registration surface 38 must progressively increase from the wider end 44 (FIG. 9) toward the narrower end 46 (FIG. 8) due to the shorter distance that the slope traverses. As a result, the registration surface 38 does not lie in a flat plane, but instead is a twisted or curved surface whose curvature is important for proper and stable registration of products during the slicing operation. A technique for generating the progressively increasing slope of the registration surface 38 is to fixture the knife holder 34 so that a twist is induced in the holder 34 prior to machining the holder 34 to form the registration surface 38. The degree of twist is carefully established and maintained during machining of the holder 34 so that when the holder 34 is released from the fixture, the slope of the registration surface 38 progressively increases corresponding to the degree of twist during machining.
As shown in FIG. 10, unsliced products 48 are advanced on a conveyor belt 50 toward the wheel 22 in a feed direction. The products 48 are conveyed in a manner such that each product 48 is individually supported in a zone between a terminus of the conveyor 50 (the region of the conveyor 50 where the food product 48 separates from the conveyor 50 as it engages the cutting wheel 22). Within this zone, each product 48 is sliced by the blades 32 of the cutting wheel 22 while supported by a supporting surface 54, represented in FIG. 10 as being defined by an “apron” (or shear edge) member 52 that has a shear edge 56 at which the supporting surface 54 terminates. The aforementioned slice thickness gap defined by the axial offset between the registration surface 38 at the trailing edge 40 of one knife assembly and the cutting edge 36 of the blade 32 of the trailing knife assembly 28 is evident from FIG. 10, as is the uniform thickness of a slice 58 produced by the trailing knife assembly 28. As disclosed in U.S. Pat. No. 6,792,841, the apron member 52 promotes the ability with which the cutting wheel 22 is able to precisely and uniformly slice round products, in part as a result of its supporting surface 54 sloping downwardly away from the conveyor 50. It is believed that the downward-sloping supporting surface 54 enables gravity to assist in moving the products 48 toward the knife assemblies 28 and to maintain engagement between the food products 48 and the registration surfaces 38 of the assemblies 28 as the food products 48 leave the conveyor 50. The food products 48 are initially supported by the terminal end of the conveyor 50 and then progressively supported by the supporting surface 54 of the apron member 52 while the food product 48 moves downwardly toward the shear edge 56.
Refinements to the radial cutting blades of slicing machines of the type described above have enabled production of precise, thin, uniform-thickness slices of various products. However, certain challenges are encountered when larger cutting wheels are required for cutting relatively large products, for example, cabbages, lettuce, potatoes, and meat products exceeding about 10 cm. For example, slicing of large products requires a more positive registration of the product against the registration surface 38 of each knife assembly 28 because the linear speed at the outermost radial extent of a larger wheel 22 is relatively greater and the product plane face (the planar surface generated on the product once it is sliced) will need a larger registration surface 38 in order to maintain a high degree of precise slice thickness. Furthermore, the rate at which the slope of the registration surface 38 progressively increases is different for knife holders 34 sized for use in wheels 22 of different diameters, and the machining or forming of the registration surfaces 38 and their progressively increasing slopes incur manufacturing costs.